Honestly it's such a shame because the mc is a sweetheart but the ml is kinda ruining it for me (spoilers)
1. The novel (being translated) is further ahead and the reviews say it's an unrequited love from eyra and the ml doesn't like him at all but has some interest hence the 3%. I guess you can see it as the ml playing along because he has nothing better to do and him being a dragon and all, he sees humans like ants so him going out with eyra is like an act of benevolence from him since eyra confessed.
2. Even at 100 chapters in the novel his rapport is at 10% -_-
3. He's often had lovers during his 10 year stay at solath (like eyra) so he can find his mate, to act like an acceptable lover and treat them well he imposed rules, like no cheating, abuse and killing.
4. Latter half of novel he finds out that eyra can't be his mate because he didn't live in solath most of his life, eyra breaks up with him and made a deal to find his mate before some time limit (destruction date of solath). Eyra finds his ideal mate (looks like him), he gets jealous that ml is treating him well on their date (like a gentleman) but the mate was actually a slime disguised as a human, ml gets mad and says the deals off, he tries to destroy one of the town outskirts but eyra stopped him and fought back. Eyra fighting back and actually holding him off, made his rapport points increase to 35% then as they continue fighting it eventually hits 100%.
5. The ml now falls harder in love with eyra then eyra to him.
My thoughts: ML is trash he only fell in love after fighting him -_- and he probably would've ended up happily with his ideal mate if he wasn't a slime. I don't know, the spoilers are putting me off because it meant that the time spent together meant nothing to him, it wasn't his personality that made him fall and the audacity to tell him he can't be his mate since he didn't grow up in solath which lead to their break up.
EDIT: There are some people who have read the novel (via korean raws) who give more details in the comments but at the end of the day all these spoilers are coming from people who have read the novel through MTL so the details defer from person to person due to interpretation, so it's up to you whose spoilers you take to heart.
But the general consensus is that most of ML's personality and actions are explained away by the fact that he's a dragon so we shouldn't judge him according to human standards, if that doesn't bother you then you should continue reading! Eyra and the plot is well worth the ride.
Source of my spoilers: https://www.novelupdatesforum.com/threads/show-me-your-stats-i-see-your-stats-%EB%84%88%EC%9D%98-%EC%8A%A4%ED%83%AF%EC%9D%B4-%EB%B3%B4%EC%97%AC.164732/
https://www.novelupdates.com/series/show-me-your-stats/